Ability of monovalent cations to replace potassium during stimulation of lymphoid cells |
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Authors: | David A Hart |
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Institution: | Department of Microbiology, University of Texas Health Science Center, Dallas, Texas 75235 U.S.A. |
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Abstract: | Stimulation of hamster thymocytes, splenocytes, or lymph node cells occurred to a minimal extent in the absence of K+. This observation was found for stimulation by T-cell mitogens (phytohemagglutinin and concanavalin A), A B-cell mitogen (lipopolysaccharide), or antigen (KLH). Marginal restoration of the responses to these stimulants occurred in the presence of 0.1 mM K+ and responsiveness returned to near maximal levels on addition of 1 mM K+ to the cultures. Attempts to restore the responsiveness with other monovalent cations revealed an order of effectiveness of K+ ≥ Rb+ ? NH4+ ≥ Li+. At the 1 mM level K+ and Rb+ were equally effective in supporting stimulation by phytohemagglutinin while all concentrations of Li+ tested (0.1–10 mM) would not support stimulation. However, addition of Li+ to cultures reconstituted with 1 mM K+ or Rb+ revealed that this ion could enhance the phytohemagglutinin response by approximately 100% in the presence of K+ and only 30% in the presence of Rb+. These data support the hypotheses that the Na,K ATPase must be active for lymphocyte stimulation to occur and that some of the biological effects of Li+ on lymphocyte stimulation are mediated at the level of the Na,K ATPase. |
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